Methods and control systems of resistance adjustment of resistors

ABSTRACT

Embodiments include methods, computer systems and computer program products for controlling resistance value of a resistor in a circuit. Aspects include: retrieving, via a controller, a set of parameters of the resistor from a non-volatile memory in the circuit, detecting, via the controller, an operating temperature of the resistor during circuit operation in field using a temperature sensor, generating, by the controller, a temperature difference between the operating temperature detected and a target temperature at which the resistor has a target resistance value, producing, by the controller, a control signal responsive to the temperature difference generated, and transmitting the control signal to a temperature regulator placed adjacent to the resistor to adjust the resistance value of the resistor. The resistance value of the resistor varies in response to temperature changes around the resistor according to a temperature coefficient of the resistance of the resistor.

BACKGROUND

The present disclosure relates generally to integrated circuits, andmore particularly to methods and control systems of resistanceadjustment of resistors.

Resistors are important components of many analog electronic circuits,digital electronic circuits, discrete electronic circuits, andintegrated circuits (IC). During the production of these resistors,variations in the resistance values of these resistors are generallyunavoidable. These variations may cause performance variations for thecorresponding electronic circuits, or differences of outputs of theseelectronic circuits. For example, performance variation of a high-speedanalog circuit such as differential amplifier with a resistive load aremainly determined by the process, voltage, and temperature (PVT)variations of the precision resistors used in such high-speed analogcircuit. Consistent and precise resistance values of the resistors usedin these electronic circuits ensure consistent, reliable and dependableperformance of these electronic circuits.

Therefore, heretofore unaddressed needs still exist in the art toaddress the aforementioned deficiencies and inadequacies.

SUMMARY

In an embodiment of the present invention, a method for controlling aresistance value of a resistor in a circuit may include: retrieving, viaa controller, a set of parameters of the resistor from a non-volatilememory in the circuit, detecting, via the controller, an operatingtemperature of the resistor during circuit operation in field using atemperature sensor, generating a temperature difference between theoperating temperature detected and a target temperature at which theresistor has a target resistance value, producing, via the controller, acontrol signal responsive to the temperature difference generated, andapplying the control signal to a temperature regulator placed adjacentto the resistor to adjust the resistance value of the resistor. Theresistance value of the resistor varies in response to temperaturechanges around the resistor according to a temperature coefficient ofthe resistance of the resistor. In certain embodiments, the temperatureregulator may include a field effect transistor (FET) for changingtemperature in response to the control signal received from thecontroller, and a front end of the line (FEOL) cooler for changingtemperature in response to the control signal received from thecontroller.

In another embodiment of the present invention, a control system foradjusting a resistance value of a resistor in a circuit is provided. Incertain embodiments, the control system may include the resistor, and acontroller. The resistance value of the resistor varies in response totemperature changes around the resistor according to the temperaturecoefficient of the resistance of the resistor. In certain embodiments,the controller is configured to: retrieve the set of parameters of theresistor from the non-volatile memory in the circuit, detect anoperating temperature of the resistor during circuit operation in field,generate a temperature difference between the operating temperature anda target temperature at which the resistor has the target resistancevalue, produce a control signal responsive to the temperature differencegenerated, and apply the control signal to a temperature regulatorplaced adjacent to the resistor to adjust the resistance value of theresistor.

In yet another embodiment of the present invention, the presentdisclosure relates to a non-transitory computer storage medium. Incertain embodiments, the non-transitory computer storage medium storesinstructions. When these instructions are executed by a controller in acircuit, these instructions cause the controller to perform: retrievinga set of parameters of a resistor from a non-volatile memory in thecircuit, detecting an operating temperature of the resistor duringcircuit operation in field, generating a temperature difference betweenthe operating temperature and a target temperature at which the resistorhas a target resistance value, producing a control signal responsive tothe temperature difference generated, and applying the control signal toa temperature regulator placed adjacent to the resistor to adjust theresistance value of the resistor.

These and other aspects of the present disclosure will become apparentfrom the following description of the preferred embodiment taken inconjunction with the following drawings and their captions, althoughvariations and modifications therein may be affected without departingfrom the spirit and scope of the novel concepts of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter which is regarded as the invention is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features and advantages ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIG. 1 is a graphical illustration of a positive temperature coefficientof resistance (TCR) of a resistor and a negative TCR of another resistorin accordance with exemplary embodiments of the present disclosure;

FIG. 2 is a structural view of an exemplary control system for adjustingresistance value of a resistor in accordance with one exemplaryembodiment of the present disclosure;

FIG. 3 is a structural view of another exemplary control system foradjusting resistance value of a resistor in accordance with anotherexemplary embodiment of the present disclosure; and

FIG. 4 is a flow chart of an exemplary method of practicing anembodiment of the present disclosure.

DETAILED DESCRIPTION

The present disclosure is more particularly described in the followingexamples that are intended as illustrative only since numerousmodifications and variations therein will be apparent to those skilledin the art. Various embodiments of the disclosure are now described indetail. Referring to the drawings, like numbers, if any, indicate likecomponents throughout the views. As used in the description herein andthroughout the claims that follow, the meaning of “a”, “an”, and “the”includes plural reference unless the context clearly dictates otherwise.Also, as used in the description herein and throughout the claims thatfollow, the meaning of “in” includes “in” and “on” unless the contextclearly dictates otherwise. Moreover, titles or subtitles may be used inthe specification for the convenience of a reader, which shall have noinfluence on the scope of the present disclosure. Additionally, someterms used in this specification are more specifically defined below.

The terms used in this specification generally have their ordinarymeanings in the art, within the context of the disclosure, and in thespecific context where each term is used. Certain terms that are used todescribe the disclosure are discussed below, or elsewhere in thespecification, to provide additional guidance to the practitionerregarding the description of the disclosure. It will be appreciated thatsame thing can be said in more than one way. Consequently, alternativelanguage and synonyms may be used for any one or more of the termsdiscussed herein, nor is any special significance to be placed uponwhether or not a term is elaborated or discussed herein. The use ofexamples anywhere in this specification including examples of any termsdiscussed herein is illustrative only, and in no way limits the scopeand meaning of the disclosure or of any exemplified term. Likewise, thedisclosure is not limited to various embodiments given in thisspecification.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this disclosure pertains. In the case of conflict, thepresent document, including definitions will control.

As used herein, “plurality” means two or more. The terms “comprising,”“including,” “carrying,” “having,” “containing,” “involving,” and thelike are to be understood to be open-ended, i.e., to mean including butnot limited to.

The term computer program, as used above, may include software,firmware, and/or microcode, and may refer to programs, routines,functions, classes, and/or objects. The term shared, as used above,means that some or all code from multiple modules may be executed usinga single (shared) processor.

The term “TCR” is temperature coefficient of resistance of a resistor.

The term “CML” stands for current mode logic, and it is generally usedto represent differential amplifier having current source for biasing,pair of transistors and their corresponding load resistors to amplifydifferential signal.

The apparatuses and methods described herein may be implemented by oneor more computer programs executed by one or more processors. Thecomputer programs include processor-executable instructions that arestored on a non-transitory tangible computer readable medium. Thecomputer programs may also include stored data. Non-limiting examples ofthe non-transitory tangible computer readable medium are nonvolatilememory, magnetic storage, and optical storage.

The present disclosure will now be described more fully hereinafter withreference to the accompanying drawings FIGS. 1-4, in which certainexemplary embodiments of the present disclosure are shown. The presentdisclosure may, however, be embodied in many different forms and shouldnot be construed as limited to the embodiments set forth herein; rather,these embodiments are provided so that this disclosure will be thoroughand complete, and will fully convey the scope of the disclosure to thoseskilled in the art.

Resistors are usually important components of any analog electroniccircuits, digital electronic circuits, discrete electronic circuit, andintegrated circuits (IC). During the production of these resistorseither as discrete components, or as a part of an integrated circuit,variations in resistance values of these resistors are generallyunavoidable. These variations may cause performance variations for thecorresponding electronic circuits, or differences of outputs of theseelectronic circuits. For example, performance variation of a high-speedanalog circuit such as differential amplifier with resistive load aremainly determined by the process, voltage, and temperature (PVT)variations of precision resistors used in such high-speed analogcircuit. Consistent and precise resistance values of the resistors usedin these electronic circuits ensure consistent, reliable and dependableperformance of these electronic circuits.

Since the variations in resistance values of these resistors aregenerally unavoidable during the production process, it is desirable tohave certain built-in mechanism to compensate the variations to ensurethe resistance values are consistent and precise when the resistors areused during circuit operation in field.

A temperature coefficient describes the relative change of a physicalproperty that is associated with a given change in temperature. For aproperty resistance R that changes by dR when the temperature changes bydT, the temperature coefficient α is defined by

$\frac{d\; R}{R} = {\alpha\;{{dT}.}}$

wherein α has the dimension of an inverse temperature and can beexpressed e.g. in 1/K or K⁻¹.

If the temperature coefficient itself does not vary too much withtemperature, a linear approximation can be used to determine the value Rof a property at a temperature T, given its value R₀ at a referencetemperature T₀:R(T)=R(T ₀)(1+αΔT),

where ΔT is the difference between T and T₀. For stronglytemperature-dependent α, this approximation is only useful for smalltemperature differences ΔT.

Referring now to FIG. 1, a graphical illustration of a positive TCRcurve 102 of a resistor and a negative TCR curve 104 of another resistorare shown in accordance with exemplary embodiments of the presentdisclosure. The positive TCR curve 102 refers to materials thatexperience an increase in electrical resistance when their temperatureis raised. Materials which have useful engineering applications usuallyshow a relatively rapid increase with temperature, i.e. a highercoefficient. The higher the coefficient, the greater an increase inelectrical resistance for a given temperature increase. The negative TCRcurve 104 refers to materials that experience a decrease in electricalresistance when their temperature is raised. Materials which have usefulengineering applications usually show a relatively rapid decrease withtemperature, i.e. a lower coefficient. The lower the coefficient, thegreater a decrease in electrical resistance for a given temperatureincrease.

A resistor that exhibits either positive TCR or negative TCR may be usedto adjust the resistance value of the resistor by adjusting thesurrounding temperature of the resistor within a certain temperaturerange.

In one aspect, the present disclosure relates to a control system 200for adjusting a resistance value of a resistor 220 in a circuit. FIG. 2shows a structural view of the exemplary control system 200 foradjusting resistance value of a resistor 220 in accordance with oneexemplary embodiment of the present disclosure. The control system 200may include: a resistor 220, a temperature regulator 210, a controller(not shown in FIG. 2), and a substrate 240. The resistor 220 has a firstterminal electrically coupled to a first via 222, and an opposite,second terminal electrically coupled to a second via 224. The first via222 is electrically coupled to a first terminal 232 of the resistor 220,and the second via 224 is electrically coupled to a second terminal 234of the resistor 220. The resistor 220 is a part of an electroniccircuit. The electronic circuit may be a discrete electronic circuit, oran integrated circuit.

In certain embodiments, the temperature regulator 210 is a field effecttransistor (FET). The temperature regulator 210 may include a gateterminal 212, a source terminal 214, and a drain terminal 216. Thetemperature regulator 210 may be placed under, or adjacent to theresistor 220, and is used to generate certain amount of heat to changethe temperature of the resistor 220 when the temperature regulator 210is energized by the controller. The control system 200 may include atemperature sensor 250 to measure the temperature of the resistor 220while the electronic circuit is in operation.

In certain embodiments, the controller is coplanar with temperatureregulator 210 and not shown in the cross sectional view. The temperatureregulator 210 may include an FET, or an FEOL cooler. In one embodiment,the substrate 240 may be a bulk silicon substrate. In anotherembodiment, the substrate 240 may be a silicon on insulator (SOI) andsilicon substrate.

According to the design of the electronic circuit, the resistor 220 maybe given a target resistance value, R_(t). However, when the resistor220 is chosen to be installed in a discrete electronic circuit, or isintegrated in an integrated circuit (IC) chip, an actual resistancevalue R₁ may not be exactly the same as the target resistance value,R_(t). The resistance discrepancy (R_(t)−R₁) may cause the performanceof the electronic circuit to deteriorate.

In one embodiment, the temperature sensor 250, the temperature regulator210, and the controller are placed under or adjacent to the resistor 220to compensate the resistance discrepancy (R_(t)−R₁). For example, in oneembodiment, the resistance discrepancy (R_(t)−R₁)>0, where the R₁ isless than the target resistance R_(t). The controller should raise thetemperature of the resistor 220, hence raise the resistance value of theresistor 220 to compensate the resistance discrepancy (R_(t)−R₁). Thecontroller first retrieves a set of parameters of the resistor 220 froma non-volatile memory of the electronic circuit. The set of parametersof the resistor 220 may include: the target resistance value R_(t), aninitial resistance value R₀ measured at wafer test, an initialtemperature associated with the initial resistance value measured atwafer test, and a temperature coefficient of the resistance (TCR)measured at the wafer test. Then the controller detects an operatingtemperature of the resistor 220 during circuit operation in field usingthe temperature sensor 250, generates a temperature difference betweenthe operating temperature detected and a target temperature at which theresistor 220 has the target resistance value, produces a control signalresponsive to the temperature difference generated, and then applies thecontrol signal to the temperature regulator 210 to adjust the resistancevalue of the resistor 220 by changing the temperature of the resistor220 to raise the resistance value of the resistor 220 until theresistance value of the resistor 220 reaches the target resistanceR_(t).

In another embodiment, the resistance discrepancy (R_(t)−R₁)<0, wherethe R₁ is greater than the target resistance R_(t). The controllershould reduce the temperature of the resistor 220, hence reduce theresistance value of the resistor 220 to compensate the resistancediscrepancy (R_(t)−R₁). The controller first retrieves a set ofparameters of the resistor 220 from the non-volatile memory of theelectronic circuit. Then the controller detects the operatingtemperature of the resistor 220 during circuit operation in field usingthe temperature sensor 250, generates a temperature difference betweenthe operating temperature detected and a target temperature at which theresistor 220 has the target resistance value, produces a control signalresponsive to the temperature difference generated, and then applies thecontrol signal to the temperature regulator 210 to adjust the resistancevalue of the resistor 220 by changing the temperature of the resistor220 to reduce the resistance value of the resistor 220 until theresistance value of the resistor 220 reaches the target resistanceR_(t).

In the embodiments described above, a resistor that has a positive TCRcurve is used. The resistance value of the resistor increases as thetemperature of the resistor increases. Here an FET heater may be used tochange the resistance value of the resistor.

In other embodiments, a resistor that has a negative TCR curve may beused. The resistance value of the resistor decreases as the temperatureof the resistor increases. Here a front end of line (FEOL) cooler suchas forward biased PN junction Peltier cooler may be used to change theresistance value of the resistor.

FIG. 3 shows a structural view of another exemplary on-chip controlsystem 300 for adjusting resistance value of a resistor 320 in anintegrated circuit in accordance with one exemplary embodiment of thepresent disclosure. The control system 300 may include: a resistor 320,a temperature regulator 310, a controller 340, and a substrate 340. Theresistor 320 has a first terminal electrically coupled to a first via322, and an opposite, second terminal electrically coupled to a secondvia 324. The first via 322 is electrically coupled to a first terminal332 of the resistor 320, and the second via 324 is electrically coupledto a second terminal 334 of the resistor 320. The resistor 320 is a partof the integrated circuit.

In certain embodiments, the controller is coplanar with temperatureregulator 310 and not shown in the cross section view. The temperatureregulator 310 may include an FET, or an FEOL cooler. In one embodiment,the substrate 340 may be a bulk silicon substrate. In anotherembodiment, the substrate 340 may be a silicon on insulator (SOI) andsilicon substrate.

In certain embodiments, the temperature regulator 310 may be an FET. Thetemperature regulator 310 may include a gate terminal 312, a sourceterminal 314, and a drain terminal 316. The temperature regulator 310may be placed under, or adjacent to the resistor 320, and is used togenerate certain amount of heat to change the temperature of theresistor 320 when the temperature regulator 310 is energized by thecontroller. The control system 300 may include a temperature sensor 350to measure the temperature of the resistor 320 while the electroniccircuit is in operation. The operating principle here are parallel tothe ones described in previous sections, and will not be repeated herefor brevity reasons.

In certain embodiments, the temperature regulator 310 is biased, and itsparasitic capacitance impact can be substantial in the integratedcircuit. Due to the distributed nature of parasitic resistance andcapacitance (RC), such parasitic capacitance may be neutralized orminimized by placing the temperature regulator 310 in certain locationwhen the integrated circuit is designed. For example, as shown in FIG.3, the resistor 320 is used in a differential amplifier such as currentmode logic (CIVIL). The first terminal 332 of the resistor 320 iselectrically coupled to an output terminal of the differentialamplifier, and the second terminal 334 of the resistor 320 iselectrically coupled to an IC power supply pin VDD or ground (GND). Inorder to minimize the parasitic capacitance of the integrated circuit,the temperature regulator 310, or the FET, is placed near the secondterminal 334, i.e., near IC power supply pin VDD or the ground (GND) tominimize the potential impact of the parasitic capacitance.

In another aspect, the present disclosure relates to a method forcontrolling resistance value of a resistor 220 in a circuit. Referringnow to FIGS. 2 and 4, the structural view of the exemplary controlsystem 200 for adjusting resistance value of the resistor 220 and a flowchart of an exemplary method 400 of adjusting resistance value of theresistor 220 are shown according to certain embodiments of the presentdisclosure. As shown at block 402, the controller retrieves a set ofparameters of the resistor 220. The set of parameters is stored in anon-volatile memory device (not shown in FIG. 2) of the electroniccircuit. In certain embodiments, the set of parameters may include: atarget resistance value, an initial resistance value measured at wafertest, an initial temperature associated with the initial resistancevalue measured at the wafer test, and a temperature coefficient of theresistance (TCR). The resistor 220 may be a resistor that has positivetemperature coefficient of resistance, or a thermistor. The resistancevalue of the resistor varies in response to temperature changes aroundthe resistor 220 according to the temperature coefficient of theresistance of the resistor 220.

Next, as shown at block 404, the controller detects current operatingtemperature of the resistor 220 during circuit operation in field. Thecontroller may use the current operating temperature of the resistor 220to calculate current resistance value of the resistor 220 according tothe temperature coefficient of the resistance of the resistor 220retrieved through block 402.

As shown at block 406, the controller generates a temperature differencebetween the current operating temperature detected and a targettemperature at which the resistor 220 has the target resistance value.The target temperature is calculated based on the initial resistancevalue and the temperature coefficient of resistance of the resistor 220.

As shown at block 408, the controller produces a control signalresponsive to the temperature difference generated. The controller firstdecides whether the temperature of the resistor 220 should go up or downbased on the temperature difference detected. When the resistor has apositive TCR, and the when the target resistance value is higher thanthe current resistance value, then the controller may increase thevoltage or current to the temperature regulator 210 to increase theresistance value of the resistor 220. When the resistor has a negativeTCR, and the when the target resistance value is less than the currentresistance value, then the controller may increase the voltage orcurrent to the temperature regulator 210 to decrease the resistancevalue of the resistor 220.

At block 410, the controller checks whether the current resistance valueof the resistor 220 has reached the target resistance value. When thecurrent resistance value of the resistor 220 has reached the targetresistance value, then the method 400 continues to block 412. When thecurrent resistance value of the resistor 220 is still greater than orless than the target resistance value, then the method 400 continues toblock 406 to continue the resistance value adjustment until the currentresistance value of the resistor 220 reaches the target resistancevalue.

At block 412, the controller continues to monitor and adjust the currentresistance value of the resistor 220 when necessary, until theelectronic circuit is shut down.

In yet another aspect, the present disclosure relates to anon-transitory computer storage medium. In certain embodiments, thenon-transitory computer storage medium stores instructions. When theseinstructions are executed by a controller in a circuit, theseinstructions cause the controller to perform: retrieving a set ofparameters of a resistor 220 from a non-volatile memory in the circuit,detecting an operating temperature of the resistor 220 during circuitoperation in field, generating a temperature difference between theoperating temperature and a target temperature at which the resistor 220has a target resistance value, producing a control signal responsive tothe temperature difference generated, and applying the control signal toa temperature regulator 210 placed adjacent to the resistor 220 toadjust the resistance value of the resistor 220.

In certain embodiments, the set of parameters of the resistor 220 mayinclude: the target resistance value, an actual resistance valuemeasured at wafer test, and a temperature coefficient of the resistanceat the wafer test. In certain embodiments, the resistance value of theresistor 220 varies in response to temperature changes around theresistor 220 according to the temperature coefficient of the resistanceof the resistor 220.

In certain embodiments, the non-transitory computer storage medium mayinclude instructions for detecting the temperature of the resistor 220using a temperature sensor 250. The temperature regulator 210 may be afield effect transistor (FET) for changing temperature in response tothe control signal received from the controller, and a front end of theline (FEOL) cooler for changing temperature in response to the controlsignal received from the controller.

In certain embodiments, the non-transitory computer storage medium mayinclude instructions for calculating the target temperature of theresistor 220 at which the resistor 220 has the target resistance valueaccording to the actual resistance value and the temperature coefficientof resistance of the resistor 220 measured at wafer test.

The present invention may be a computer system, a method, and/or acomputer program product. The computer program product may include acomputer readable storage medium (or media) having computer readableprogram instructions thereon for causing a processor to carry outaspects of the present invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, and computerprogram products according to embodiments of the invention. It will beunderstood that each block of the flowchart illustrations and/or blockdiagrams, and combinations of blocks in the flowchart illustrationsand/or block diagrams, can be implemented by computer readable programinstructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

What is claimed is:
 1. A method for controlling resistance value of aresistor in a circuit comprising: retrieving, via a controller, aplurality of parameters of the resistor from a non-volatile memory inthe circuit; detecting, via the controller, an operating temperature ofthe resistor during circuit operation in field; generating, by thecontroller, a temperature difference between the operating temperaturedetected and a target temperature at which the resistor has a targetresistance value; producing, by the controller, a control signalresponsive to the temperature difference generated; and transmitting thecontrol signal to a temperature regulator placed adjacent to theresistor to control the resistance value of the resistor, wherein thetemperature regulator comprises a field effect transistor (FET)configured to change temperature of the resistor in response to thecontrol signal received from the controller.
 2. The method of claim 1,wherein the plurality of parameters of the resistor comprises: aninitial resistance value measured at wafer test; an initial temperatureassociated with the initial resistance value measured at the wafer test;the target resistance value; and a temperature coefficient of theresistance measured at the wafer test.
 3. The method of claim 2, whereinthe resistance value of the resistor varies in response to temperaturechanges around the resistor according to the temperature coefficient ofthe resistance of the resistor.
 4. The method of claim 1, wherein thedetecting comprises detecting the operating temperature of the resistorusing a temperature sensor.
 5. The method of claim 1, wherein thetemperature regulator comprises a front end of the line (FEOL) coolerconfigured to change temperature of the resistor in response to thecontrol signal received from the controller.
 6. The method of claim 1,wherein the generating comprises calculating the target temperature ofthe resistor at which the resistor has the target resistance valueaccording to the initial resistance value and the temperaturecoefficient of resistance of the resistor measured at wafer test.
 7. Acontrol system for adjusting a resistance value of a resistor in acircuit comprising: the resistor having a plurality of parameters of theresistor stored in a non-volatile memory in the circuit, wherein theplurality of parameters comprises an initial resistance value measuredat wafer test, an initial temperature associated with the initialresistance value measured at the wafer test, a target resistance value,and a temperature coefficient of the resistance measured at the wafertest; a temperature regulator located adjacent to the resistor, whereinthe temperature regulator comprises a field effect transistor (FET)configured to change temperature in response to the control signalreceived from the controller; and a controller configured to: retrievethe plurality of parameters of the resistor from the non-volatile memoryin the circuit; detect an operating temperature of the resistor duringcircuit operation in field; generate a temperature difference betweenthe operating temperature and a target temperature at which the resistorhas the target resistance value; produce a control signal responsive tothe temperature difference generated; and transmit the control signal tothe temperature regulator to adjust the resistance value of theresistor.
 8. The control system of claim 7, wherein the resistance valueof the resistor varies in response to temperature changes around theresistor according to the temperature coefficient of the resistance ofthe resistor.
 9. The control system of claim 7, wherein the controlleris configured to detect the operating temperature of the resistor usinga temperature sensor.
 10. The control system of claim 7, wherein thetemperature regulator comprises a front end of the line (FEOL) coolerconfigured to change temperature in response to the control signalreceived from the controller.
 11. The control system of claim 7, whereinthe controller is configured to calculate the target temperature of theresistor at which the resistor has the target resistance value accordingto the initial resistance value and the temperature coefficient ofresistance of the resistor measured at wafer test.
 12. A circuitcomprising the control system of claim
 7. 13. A non-transitory computerstorage medium having instructions stored thereon which, when executedby a controller in a circuit, cause the controller to perform:retrieving a plurality of parameters of a resistor from a non-volatilememory in the circuit; detecting an operating temperature of theresistor during circuit operation in field; generating a temperaturedifference between the operating temperature and a target temperature atwhich the resistor has a target resistance value; producing a controlsignal responsive to the temperature difference generated; andtransmitting the control signal to a temperature regulator placedadjacent to the resistor to adjust the resistance value of the resistor,wherein the temperature regulator comprises a field effect transistor(FET) configured to change temperature of the resistor in response tothe control signal received from the controller.
 14. The non-transitorycomputer storage medium of claim 13, wherein the plurality of parametersof the resistor comprises: the target resistance value; an initialresistance value measured at wafer test; an initial temperatureassociated with the initial resistance value measured at the wafer test;and a temperature coefficient of the resistance at the wafer test. 15.The non-transitory computer storage medium of claim 14, wherein theresistance value of the resistor varies in response to temperaturechanges around the resistor according to the temperature coefficient ofthe resistance of the resistor.
 16. The non-transitory computer storagemedium of claim 13, wherein the detecting comprises detecting theoperating temperature of the resistor using a temperature sensor. 17.The non-transitory computer storage medium of claim 13, wherein thetemperature regulator comprises: a front end of the line (FEOL) coolerconfigured to change temperature in response to the control signalreceived from the controller.
 18. The non-transitory computer storagemedium of claim 13, wherein the generating comprises calculating thetarget temperature of the resistor at which the resistor has the targetresistance value according to the initial resistance value and thetemperature coefficient of resistance of the resistor measured at wafertest.